If you are focusing on Fire-damage only farms in AE, you want to make sure you have 45% defense to Fire and 90% resistance to Fire. Then focus on recharge and then damage procs on Burn and the AoEs.
If you are focusing on Lethal, Smashing, and Fire Damage in AE or outside of AE, I started a thread about using my Radiation Melee / Fire Armor Brute secondary build for this purpose. I used Outrider's build in the thread and I farm Peregrine Island Portal missions for this purpose: